<!DOCTYPE html>
<html class=reftest-wait>
<title>View transitions: root element style changes during transition</title>
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/">
<link rel="author" href="mailto:vmpstr@chromium.org">
<link rel="match" href="root-style-change-during-animation-ref.html">
<script src="/common/reftest-wait.js"></script>
<style>
#target {
  width: 100px;
  height: 100px;
  contain: paint;
  background: blue;
  view-transition-name: target;
}

#hidden {
  background: pink;
  width: 10px;
  height: 10px;
  view-transition-name: hidden;
  contain: paint;
}

html::view-transition {
  background: grey;
}

html::view-transition-group(hidden) {
  animation-duration: 500s;
  visibility: hidden;
}

html::view-transition-group(root) {
  visibility: hidden;
}

.test::view-transition-group(target) {
  background: green;
}
.test::view-transition-image-pair(target) {
  visibility: hidden;
}
</style>

<div id=target></div>
<div id=hidden></div>

<script>
failIfNot(document.startViewTransition, "Missing document.startViewTransition");

function flipClass() {
  document.documentElement.classList.add("test");
  requestAnimationFrame(takeScreenshot);
}

async function runTest() {
  document.startViewTransition(() => {
    hidden.style.width="20px";
    requestAnimationFrame(() => requestAnimationFrame(flipClass));
  });
}
onload = () => requestAnimationFrame(() => requestAnimationFrame(runTest));
</script>

